<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<textarea onkeydown="clickA(event)"></textarea>
<script>
    function clickA(e){
        if (e.keyCode ==13){
            e.preventDefault();
            e.stopPropagation();
        }
    }
</script>
</body>
</html>